View
220
Download
0
Category
Preview:
DESCRIPTION
Laws of thermodynamics, entropy, irreversible processes, Gibbs free energy law. Chemistry and Mathematics used to describe laws of motion etc.
Citation preview
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 1/42
ThermodynamicsChapter 18
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 2/42
1st Law of Thermodynamics
Energy is conserved.
∆E = q + w
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 3/42
SP!T"!E#S$ occ%r witho%tany o%tside intervention
E&'e$ drop an egg
The (E)E(SE is not spontaneo%s**
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 4/42
(E)E(S,LE P(CESS$ change
can -e restored to its origina' state -y e&act'y reversing the change .
E&'e$ ice water at /o C
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 5/42
((E)E(S,LE P(CESS$
cannot simp'y -e reversed toorigina' state.
E&'e$ gas e&panding
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 6/42
Processes in which the
disorder of the system
increases tend to occ%rspontaneously.
E&$ gas e&panding0 ice me'ting0 sa't disso'ving
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 7/42
E!T(P$ 2S3 the change in
disorder. 2Change in randomness3The more disorder0 the 'arger the
entropy.
∆S = Sfina' 4 Sinitia'
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 8/42
∆S = 5 / when the fina' state is
in more disorder
∆S = 6 / when the fina' state
is more ordered than origina'
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 9/42
7 2'3 ⇔ 7 2s3
"g
+
2aq3 + C'
4
2aq3
→ "gC'2s3
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 10/42
4 a so'id me'ts
4 a 'iq%id vapori9es
4 a so'id disso'ves in water
4 a gas 'iq%efies
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 11/42
:or a process at constant
temperat%re0 the entropychange is the va'%e of qrev
divided -y the a-so'%tetemperat%re.
∆S = qrev;T
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 12/42
E&'e$ Ca'c%'ate the entropy
change when 1 mo' of water isconverted into 1 mo' of steam at
1 atm press%re. 2∆7vap = </.>?@;mo'3
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 13/42
21 mo'e32</.> ?@; mo'321/// @;1 ?@3
A>A B
∆S = 1/ @;B
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 14/42
The norma' free9ing point of
merc%ry is 4A8.oC0 an itsmo'ar entha'py of f%sion is
∆7f%s = .AA1 ?@;mo'. Dhat is
the entropy change when /./
g of 7g2'3 free9es at the
norma' free9ing pointF
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 15/42
4.<8 @;B The answer is negative -eca%se the
process -rings more order
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 16/42
The norma' -oi'ing point of
ethano'0 is >8.AoC and its mo'arentha'py of vapori9ation is A8.
?@;mo'. Dhat is the change inentropy when .8 g of
C772g3 condenses to 'iq%id atthe norma' -oi'ing pointF
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 17/42
41.< @;B
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 18/42
The e'ement ga''i%m0 Ga0
free9es at .8oC0 and itsentha'py of f%sion is .
?@;mo'. Ca'c%'ate the
va'%e of ∆S for thefree9ing of /./ g of Ga2'3.
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 19/42
∆S = 4A.8 @;B
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 20/42
nd Law of Thermodynamics$ n any
reversi-'e process0∆
S%niverse = /. n anyirreversi-'e 2spontaneo%s3 process0
∆S%niverse 5 /.
∆S%niverse = ∆Ssystem + ∆Ss%rro%ndings
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 21/42
On a Molecular Level
T("!SL"T!"L HT!$ movement of
mo'ec%'es
),("T!"L HT!$ the movement of
atoms within the mo'ec%'e.
(T"T!"L HT!$ the mo'ec%'es
spinning
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 22/42
ncreasing Temperat%re ncreases Entropy
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 23/42
Ard Law of Thermodynamics$ the
entropy of a p%re crysta''ine
s%-stance at a-so'%te 9ero is 9ero.
S2/B3 = /
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 24/42
In general, the entropy increases when$
Liq%ids or so'%tions are formed from so'ids
Gases are formed from either so'ids or
'iq%ids
The n%m-er of mo'ec%'es of gas increasesd%ring a chemica' reaction.
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 25/42
CaCA2s3 → Ca2s3 + C2g3
!2g3 + A72g3 → !7A2g3
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 26/42
Standard molar entropies$ 2So3 a-so'%te
entropies for s%-stances in their standard
state. 2@;mo'4B3
1. #n'i?e entha'pies of formation0 the standard mo'ar
entropies of e'ements are not 9ero.
. The So of gases are greater than those of 'iq%ids and
so'ids.
A. The So genera''y increases with increasing mo'ar mass.
<. The So genera''y increase with the n%m-er of atoms in
the form%'a.
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 27/42
∆So = ΣnSo2prod%cts3
4 ΣmSo2reactants3
Ca'c%'ate ∆So for the synthesis of ammonia$
!2g3 + A72g3 → !7A2g3
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 28/42
∆So = 2 mo'321. @;mo'4B3 4
I21 mo'3211. @;mo'4B3 + 2Amo'321A/. @;mo'4B3J =
418.A @;B
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 29/42
#sing "ppendi& C0 ca'c%'ate the
standard entropy change0 for thefo''owing reaction$
"'A2s3 + A72g3 → "'2s3 + A72g3
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 30/42
18/.< @;B
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 31/42
C
7<2g3
+ 72g3
→ C
72g3
!7A2g3 + 7C'2g3 → !7<C'2s3
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 32/42
41/. @;B
48<. @;B
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 33/42
GIBBS FREE EERG!
The spontaneity of a reaction invo'ves -oth
entha'py and entropy. The re'ationship is
?nown as "ree energy.
∆G = ∆7 4 T∆S
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 34/42
1. f ∆G is negative0 the reaction is
spontaneo%s in the forward direction.
. f ∆G is 9ero0 the reaction is at
eq%i'i-ri%m.
A. f ∆G is positive0 the reaction in the
forward direction is nonspontaneo%sK wor?
m%st -e s%pp'ied from the s%rro%ndings to
ma?e it occ%r. 7owever0 the reverse reaction
wi'' -e spontaneo%s.
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 35/42
∆G
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 36/42
∆Go = ∑n∆Gf o2prod%cts3 4 ∑m∆Gf
o2reactants3
!2g3 + A72g3 → !7A2g3
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 37/42
4AA.A ?@
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 38/42
C7<2g3 + 2g3 → C2g3 + 72g3
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 39/42
C7<2g3 + 2g3 → C2g3 + 72g3
48//.> ?@
" i h f ∆7
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 40/42
"ss%ming no change for ∆7o
and∆
S
o
0 what happens to∆
G
o
with an increase in temperat%reF
!2g3 + A72g3 → !7A2g3
C ' ' ∆G 8B f
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 41/42
Ca'c%'ate ∆G at 8B for
a reaction mi&t%re thatconsists of 1./ atm !0 A./
atm 7 and /./ atm !7A.
!2g3 + A72g3 → !7A2g3
7/18/2019 Thermodynamics presentation
http://slidepdf.com/reader/full/thermodynamics-presentation 42/42
#se standard free energies
of formation to ca'c%'ate
the eq%i'i-ri%m constantB at oC for the reaction
invo'ved in the 7a-er process.
Recommended